Railway signaling apparatus



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Patented Sept. 24, 1940 PATENT OFFICE RAILWAY SIGNALIN G APPARATUS Claude M. Hines, Pittsburgh, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application June 23, 1939, Serial No. 280,731

14 Claims.

My invention relates to railway signaling apparatus, and has particular reference to the organization of such apparatus into railway s ignaling systems of the class wherein coded track- Way energy is utilized to control either or both wayside signals and train-carried cab signals.

It -has been proposed heretofore to employ saturation type relays, which are characterized by the fact that all the component parts thereof are stationary, as code following relays 1n connection with railway signaling systems utilizing coded trackway energy consisting of on-periods when current flows and ofi periods when no current flows. I have found that when saturation type code following relays are employed to control the decoding apparatus of such systems, improved and more ecient operation of such decoding apparatus is effected by energy supplied during only half of the code period, as for example, during only the on period of the code. Saturation type relays having but a single output winding accordingly can be employed with marked success. Also, I have found that when the decoding apparatus is supplied with energy during both the on and off periods of the code by saturation relays having two or more output windings, the energy reproduced in each output winding of such relays preferably should be supplied to separate control elements or windings of the decoding apparatus. In this manner, the short-circuiting action of the rectiiiers which convert the alternating energy output of the saturation relay output windings is minimized, and as a result of the sharp cut-off in the reproduced coded energy supplied to the decoding apparatus, improved and more efficient operation of such apparatus is effected. Accordingly, an object of my present invention is the organization of railway signaling apparatus into novel and improved forms of railway signaling systems employing code responsive relays of the saturation type.

Another object is the provision of novel and improved means whereby two signal control relays may be controlled by energy supplied from but a single output winding of a saturation type code following relay.

An additional object is to provide novel and improved-means controlled by saturation type code following relays to protect against the giving of a false proceed indication in the event of an insulation breakdown of an insulated joint which electrically separates the rails of adjacent track sections.

A further object is to provide novel and improved cut-section facilities in which code responsive relays of the saturation` type are employed'to cascade trackway energy around the insulated joints of a cut-section in a track secion.

Another object is the provision in such cutsection facilities, of means to prevent the cascading action of steady or non-coded trackway energy.

An additional object is the provision in such cut-section facilities, of means to clear out the rear subsection of two adjacent subsections.

Another object is the provision of novel and improved forms of code following relays of the saturation type.

Other objects and advantages of my invention will appear as the specification progresses.

I shall describe several forms of apparatus embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a diagrammatic view showing one form of apparatus embodying my invention. Fig. 2 is a diagrammatic view of a modified form of the apparatus shown-in Fig. 1. Figs. 3 and 4 are each diagrammatic views of further modifications of the apparatus shown in Fig. 1. Fig. 5i is a diagrammatic view showing a modification of a. portion of the appa-ratus shown' in Fig. 4. Fig. 6 is a diagrammatic view showing a modification of a portion of the apparatus shown in Fig. 3. Fig. '7 is a diagrammatic view showing still another modification of the apparatus of Fig. l.

Similar reference characters refer to similar parts in each of the several views.

Referring first to Fig. 1, the reference characters I and la designate the track rails of a stretch of railway track over which traiiic normally moves in the direction indicated in the drawing by an arrow, and which direction I shall assume to be the westbound direction. The rails l and ,la are divided by means of the usual insulated rail joints 2 into a plurality of successive adjoining track sections, .of which only one section, 3 4, is shown complete in the drawing. Since the normal direction of traffic is westbound or from right to left as viewed in Fig. 1, section 3 4 constitutes an advance section with respect to the section next to the right of section 3 4 and such section constitutes a rear section with respect to section 3 4. Section 3 4 also is further divided into a plurality of subsections, formed by interposing insulated joints 2 in the rails of section 3 4 at so-called cut-section locations. As shown, the rails I and la of Fig. 1

are provided with insulated joints 2 at cut-section location 3a, with the result that section 3-4 is divided into an advance subsection 3-3a and a rear subsection 3a-4.

Each track section is provided with a signa-l, designated by the reference character S with a distinguishing suffix, located adjacent the entrance end, of the section for governing trafc operating thereover. Signals S may take any one of ma-ny suitable forms but in the form herein shown are three-indication signals of the color light type, and each signal comprises a red lamp R a yellow lamp Y and a green lamp G, which lamps when illuminatedindicate stop, caution and proceed," respectively.

Each section is provided with means, located at the leaving end of the section, for supplying to the rails of the associated section coded trackway energy, the code frequency or rate of which is controlled by traiiic conditions in advance. These means are herein shown in the usual form and comprise for each section a track transformer, designated by the reference character TT with a distinguishing suiiix, a coding device designated by the reference character CT with a distinguishing suflix, a source of current, and a control relay designated by the reference character H plus a distinguishing suihx, which relay as will be pointed out hereinafter, is controlled by traflic conditions in the section next in advance to the section to which trackway energy is to be supplied. The secondary winding of each track transformer 'I'I is constantly connected with the rails of its associated section in series with the usual current limiting impedance 5, and the primary winding of the track transformer 'I'I' is connected with the terminals BX and CX of a source of alternating current (such as a generator not shown in the drawings) preferably of a frequency of 100 cycles per second, over one contact |80 or another contact I5 of the associated coding device CT, according as front contact 6 or back contact 'I of the relay H associated with the section next in advance is closed. Each coding device CT is constantly energized from a source of current having its terminals designated by the reference characters BX and CX, and each coding device periodically opens and closes its contact ISU at the rate of 180 times per minute, and also opens and closes its contact 15 at the rate of 75 times per minute. It is readily apparent, therefore, that when the relay H of a section is picked up so that its front contact 6 is closed, the rails of the section next in therear are supplied with alternating trackwayY energy which is periodically interrupted or coded at the rate of 180 times per minute, but that, when the relay H of a section is released so that its back contact 1 is closed, the rails of the section next in the rear then are supplied with alternating trackway energy which is periodically interrupted or coded at the rate of 75 times per minute. The 180 code is used to provide a proceed indication and the 75 code is used to provide a caution indication for the signal of the associated section, in a manner which will be made clear as the description proceeds. It will be understood, of course, that while only the means for supplying coded trackway energy to the section next in the rear of section 3 4 is shown in its entirety in Fig. 1, and which apparatus comprises the coding device CT4 and track transformer TT4 associated with the section next in the rear of section 3 4, and relay H4 associated with section 3 4, the primary winding of track transformer TT3 (located at the exit end oi' section 3 4) is supplied' with coded alternating current in the same manner that the apparatus set forth above supplies the primary winding of track transformer 'IT4 with coded alternating current, the coding device CT and control relay H associated with transformer 'II'3 being omitted from the drawings for the sake of simplicity since it would be but a duplication of the coding device CT4 and relay H4 shown associated with track transformer TI4.

Each section is provided at its entrance end with a code following track relay which I shall term a front contact relay of the saturation type, designated by the reference character DR with a distinguishing suix. A similar relay is located also at the cut-section location of each section, only the relays DRI and DRIa located respectively at the signal location 4 and at the cut-section location 3a of section 3 4, being shown in the drawing. The relays DR are substantially similar in construction so that the following description of relay DRIa will suillce as well to describe relay DRI. I

Relay DRIa, in the form herein shown, comprises a magnetizable core 8 provided With`four legs 9, I0, II and I2 connected together at each end to form an integral relay core structure. One of the inner legs II is provided with al primary or local input winding I3, constantly connected with a source of alternating current designated by the terminals BX and CX, and as shown the adjacent outer leg I2 is provided with a secondary or output winding I4. It is to be understood, of course, that additional output windings may, if desired, be mounted on outer leg I2, in which event each output winding functions in a manner to be made clear presently, as a front contact output winding. The other two legs 9 and I0 are provided with a control or saturation winding I5, which comprises two coils I5a and I5b disposed on legs 9 and I0, respectively, and connected in series in such manner that current owing in these two coils will cause the coils to act cumulatively to circulate a flux around the closed path formed by the associated legs 9 and I0 of the core. 'I'his arrangement of coils I5a and I5b is, therefore, such that any voltages induced therein in response to the alternating current owing in primary winding I2 oppose each other.

The control or saturation Winding I5 of the relay DRIa. is supplied with energy from the associated track rails I and Ia of subsection 3 3a, through the medium of a relay transformer RT3a, which insulates winding I5 from such track rails, and a rectifier RI which converts the coded alternating trackway energy received from the rails into and supplies winding I5 with impulses of unidirectional current. 'I'he parts are so proportioned that when current is supplied to winding I5, as for example, during the on period of the code, the magnetic flux created by such current will saturate the legs 9 and IllV of core 8, so that these two legs will have a high reluctance to the primary ux created by input winding I3.

'I'he output winding I4 of relay DRIa is connected across the track rails I and Ia of subsection 3a-4 for a purpose to be made clear presently.

With relay DRIa, constructed and arranged in the foregoing manner, it can be seen that its input winding I3, being constantly supplied with alternating current, supplies a primary iiux which may circulate through core 8 through twomagnetic circuits, one circuit of which includes corev leg I2, and the other circuit of which includes in parallel the core legs 9 and I0. It is apparent that during the interval that the primary flux divides between its two magnetic circuits, an electromotive force of a given magnitude will be induced by such flux in output winding I4.' When, however, control winding l is supplied with curl rent during the on period of the code so that core legs 9 and Ill are saturated and have a high reluctance, substantially al1 the primary iiux then will circulate through leg I2 `with the re,

sult that the magnitude of the electromotive force induced in output winding I4 is greatly increased over the aforementioned given electromotive force induced in winding I4 during the "ofP period of the code. It follows, therefore, that since winding I4 is connected with the track rails of subsection 3a-4, alternating trackway energy of relatively large magnitude is or is not supplied to such track rails according as control winding I5 is or is not supplied with current. 'I'he coded trackway energy supplied to the track rails of subsection 3-3a is thus reproduced in kind and is supplied to the track rails of subsection 3a4 by means of the saturation relay DRIa.

The other saturation relay DRI has its control winding supplied with energy from the track rails of subsection 3a-4 through the medium of a relay transformer RT4 and a rectifier R2. 'I'he output winding I4 of relay DRI is connected to the input terminals of a rectifier R3, the output terminals of which are in turn connected across a primary winding I6 of a decoding transformer DT I It is readily apparent, therefore, that whenever current is supplied to control winding I5 of relay DRI from the rails of section 3-4, winding I6 of transformer DTI is supplied'with impulses of unidirectional current of relatively large magnitude substantially in the same manner as has been accomplished heretofore over the front contact of a code following relay of the tractive armature type, and that these impulses will have a code rate or frequency which depends upon the rate or frequency of the code present in the track rails of section 3-4. It follows, therefore, that output Winding I4 of relay DRI functions as a front contact output winding; or in other words, an electromotive force of relatively large magnitude is supplied from output winding I4 when and only when control winding I5 of the relay is energized.

The decoding transformer DTI is provided with a secondary winding I'I which has its terminals connected across the input terminals of a rectifier R4, which rectifier iny turn has its output terminals connected tothe terminals of a code detecting relay H4 provided for section 3-4. The alternating current induced in winding I1 of transformer DTI in response to the impulses of current supplied to its winding I6 by relay DRI, is thus rectified by rectifier R4 into and supplied as unidirectional current to relay H4. This relay is a direct current relay preferably proportioned to have slow pick-up characteristics and having slow releasing characteristics by virtue of the short-circuiting action of rectifier R4 connected across its terminals, and also is so proportioned as to be effectively energized and picked up Whenever transformer DTI is receiving energy in response to either the 75 or 180 code being supplied to code following relay DRI. Relay H4, therefore, functions as a code detecting relay since it is picked up on either of the two code frequencies.

The decoding transformer DTI also supplies energy to a code selecting relay AJ4 for section fier and a reactor condenser tuning unit tuned to resonance at a frequency corresponding to the 180 code, whereby relay AJ4 is effectively energized and is picked up when and only when 180 code is-supplied by the code following relay to` the decoding transformer. Since relay AJ 4 is controlled by the unidirectional impulses supplied by relay DRI to transformer DTI, it'might be necessary to proportion the parts of decoding unit DU- I 80 in a manner to provide sufficient capacity to eliminate the ripple effect of the pulsating unidirectional current of relatively high magnitude, such as might be caused by a continued energization of control winding I5 of relay DRI.

The code selecting relay AJ4 and the code detecting relay H4 cooperate to selectively control the various aspects displayed by signal S4, in the following manner. When relays H4 and AJ 4 `are both picked up, signal S4 is caused to display its "proceed indication over a circuit which may be traced from terminal B through front contact I9 of relay H4, front contact 2U of relay AJ 4 and the filament of lamp G of signal S4 to terminal C. When the code detecting relay H4 is picked up andthe code selecting relay AJ4 is released, signal S4 then is caused to display its caution indication over a circuit passing from terminal B through front contact I 9 of relay H4, back contact 22 of relay AJ4 and the filament of lamp Y of signal S4 to terminal C. When, however, both relays H4 and AJ4 are released, signal S4 then is caused to display its stop indication over a circuit passing from terminal B through back contact 2| of relay H4 and the filament of lamp R of signal S4 to terminal C.

'Ihe above selective control of signal S4 is effected by relays H4 and AJ4 in the following manner: section 3-4 will be supplied with 180 or 75 code according as the section next in advance of section 3-4 is unoccupied or occupied. When section 3-4 is supplied with 180 code and the section is unoccupied, all parts of the apparatus will occupy the positions at which they are shown in Fig. 1. Under the above conditions, relays H4 and AJ4 are both picked up, the circuit for lamp G of signal S4 is completed whereby that signal is caused to display its proceed indication, and the circuit including front contact 6 of relay H4 and contact l80 of coding device CT4 is closed so that the section next in the rear of section 3-4 is supplied with 180 code also.

When section 3-4 is supplied with '75 code and the section is unoccupied, relay H4 is picked up but relay AJ 4 is released, thus causing signal S4 to display its caution indication since the circuit previously traced for lamp Y of signal S4 is now completed. The rails of the section next in the rear of section 34, however, are still supplied with 180 code since front contact 6 of relay H4 is closed.

When a train occupies section 3 4, the train then shunts the trackway energy away from the decoding apparatus so that relays H4 and AJ4 both release, thereby causing signal S4 to display its "stop indication. Also, with back contact 1 of relay H4 now closed, the primary winding of transformer TT4 associated with the section next in the rear of section 3-4 is connected to contact 15 of coder GT4, whereby the rails from the foregoing that the code frequency of the trackway energyl supplied to each section is governed by tramo conditions in advance of that section.

It should be noted that the apparatus of Fig. 1 controls the two signal control relays H4 and AJ4 by current supplied to the decoding transformer DTI from a. single output winding I4 of the saturation type code following relay DRI. By supplying the decoding transformer with energy from a single output winding rather than from two output windings (one of which is energized during the on period of the code and the other of which is energized during the off period) of the saturation relay, the short-cir-` cuiting action of the rectiers which convert into unidirectional current the alternating current induced in the output windings of the saturation relay is minimized, with the result that the flux decay and growth in the decoding transformer DTI is relatively rapid and relays H4 and AJ4 are quite sensitive to the different frequencies of code supplied to relay DRI.

It should further be noted that the cut-section facilities located at cut-section 3a. of Fig. 1 controls the cascading of trackway energy from one subsection into the next in a manner such that the two subsections cooperate to form a single signal control section. That is, when the' train occupies subsection 3a-4, the trackway energy then is shunted away from code following relay DRI so that both relays H4 and AJ4 are released. When the train occupies subsection 3-3a, the trackway energy then is shunted away from relay DRIa, with the result that no -coded trackway energy is supplied to the track rails of subsection 3a-4, and relays H4 and AJ4 consequently are released. If the train occupies both subsections 3-3a and 3a-4, relays H4 and AJ4 are released since not only 1s relay DRIa shunted and consequently coded trackway energy is not supplied to subsection 3a-4 but relay DIRI also is shunted.

From the foregoing, it is readily apparent that the trackway energy in one subsection is cas- -caded into the adjacent subsection by virtue of the action of the saturation relay DRIa, which reproduces in kind the coded trackway energy of the advance subsection and supplies this reproduced energy to the rear subsection. The two subsections therefore when taken together cooperate to provide a single track section, so that a train occupying any portion of the two subsections will control the associated traffic controlling apparatus in the same manner as if the track rails of section 3-4 were continuous conductors from one end of the section to the other.

It is further apparent that apparatus embodying my invention provides a signaling system of the class wherein coded trackway energy is employed to selectively control railway trafllc controlling devices, in which all rapidly moving or code following relay contacts are avoided.

A modified formi of the apparatus of Fig. 1 is shown in Fig. 2. Referring now to the latter figure, the apparatus of Fig. 1 is modified chiefly by the provision of a front and back contact" code following relay of the saturation type for the .front contact relay DRI of Fig. l. Another modification is that. for the sake of simplicity, section 2-4 of Fig. 2 is not shown divided into subsections.

The front and back contact saturation relay provided for section 2-4 of Fig. 2 is designated by the reference ycharacter DB2, and is substantially the same as relay DRI oi' Fig. 1, except that relay DR2 is provided with a second output or secondary winding 22, which comprises two coils 22a and 23h mounted on coil legs 9 and I0, respectively, and connected in series in such manner that any voltages induced therein due to flux flowing in the same direction in legs 9 and I0 are additive.

'I'he operation of relay DR2 is substantially similar to the operation previously described for saturation relays DRI and DRIa of Fig. 1, with winding 23 oi' relay DR2 acting as a back contact output winding. That is, when current is supplied to control winding II of relay DR2 during the "on period of the code, legs '2- and Il of relay DR2 become saturated so that substantially all the flux created by input winding I2 is circulated through leg I2. An electromotive force of relatively large magnitude therefore is inlay. However, when control winding I5 of relay DB2 is deenergized (as for example during the off period of the code) then the alternating flux of winding I3 is divided between its two magnetic paths so that the electromotive force induced in winding I4 is considerably reduced, and an electromotive force of relatively large magnitude is induced in second output winding 22. From the foregoing, it is readily apparent that a relatively high electromotive force is induced in winding I4 or winding 23 according as current is or is' not supplied to control winding II of relay DR2. It follows that since1 -a relatively high electromotive force is induced in rst output winding I4 only when control winding I5 is supplied with current, and a relatively high electromotive force is induced in second output winding 23 of relay DR2 only when control winding I5 is'not supplied with current, the two windings I4 and 22 correspond respectively to front and back contacts of the ordinary tractive armature type relay.

In Fig. 2, output winding I4 of relay DR2 now controls only the code detecting relay H4, and the other output winding 23 of relay DR24 controls the code selecting relay AJ 4. Control of relay H4 is established by winding I 4 of relay DR2 through the medium of a decoding transformer DT2, the. primary of which is connected through a rectifier R3 to output winding I4, and the secondary of which is vconnected through a rectifier R8 to the winding of relay H4. Transformer DT2 is proportioned so as to pick up relay H4 whenever 75 g-RBO code is supplied to code following relay Relay AJ4 is controlled by winding 23 of relay DR2 through the medium of its decoding transformer DTI, the primary of which is connected through a rectier R1 to winding 22, and the secondary of which is connected to the output terminals of rectifier R4, the input terminals of which rectifier are in turn connected across the winding of relay AJ4. The transformer DPI3 is so proportioned as to saturate quickly, so that the energy output of the transformer is constant regardless of the length of the code impulses supplied thereto, whereby relay AJ 4 is eifectively energized and is picked up by the output of transformer DT3 only when rapidly coded impulses are supplied to transformer DTB, and the relay AJ4 is energized and picked up on 180 code but is released on 75 code.

Fromthe foregoing, it is readily apparent that relays H4 and AJ4 are selectively controlled by relay DR2 in response to the frequency of the code supplied from the rails of section 3 4 to the latter relay. That is, relays H4 and AJ 4 are both picked up on 180 code; relay H4 is picked up and relay AJ4 is released on 15 code; and both relays H4 and AJ4 are released when a train occupies section 3-4 andshunts code following relay DB2.

In addition, it is readily apparent from an inspection of Fig. 2 that relays H4 and AJ4 cooperate to control signal S4, and relay H4 controls the supply of trackway energy to the section next in the rear of section 3 4, substantially in the manner pointed out in detail in connection with Fig. 1, and it is believed, therefore, that further detailed explanation of the operation of the apparatus of Fig. 2 is unnecessary.

In Fig. 3, a modified form of the apparatus of Figs. 1 and 2 is shown applied to a stretch of railway track employing electric propulsion, and in which the track rails I and la form a portion of the return circuit for the electric propulsion current. In describing the apparatus employed with electrified trackways, it is to be understood that the trackway signaling energy is alternating current of a given frequency (usually cycles per second) and that the propulsion current may be either unidirectional current or alternating current having a frequency diierent from the frequency of the signaling current. Accordingly, the current supplied from the source of alternating current (indicated as the terminals BX and CX in Fig. 3) will be assumed hereinafter to have a frequency of 100cyc1es per second.

Referring now to Fig. 3, the track layout here shown is the same as that shown in Fig. l, except that impedance bonds 25 of the customary form are provided for each pair of insulated joints 2 to conduct propulsion current around such joints. Also, since propulsion current is now present in the track rails I and Ia of section 3 4, the relay transformers RT of Fig. 1

are replaced by resonant rectier units, designated by the reference characters RU plus a distinguishing suliix. The construction of units RU is not shown in the drawing, but these units usually will include a transformer, a capacitor and a reactor so arranged and proportioned that the hundred cycle trackway signal control energy is freely passed fromthe track rails through the unit to its associated code following relay, but which unit prevents the passage of any propulsion current to the relay. Each unit also is provided with a rectifier, whereby the hundred cycle alternating trackway energy is rectified into and supplied to the associated code following relay as unidirectional current.

Two lockout relays FSA and BSA also are provided in Fig. 3 for each track section, only the relays BSA and FSA associated with section 3 4 being shown in the diagram, and which lockout relays cooperate to prevent the establishrnent of a false proceed indication in the event of an insulation breakdown of an insulated joint which separates the rails I and la into track sections. 'I'his protection is effected by means of a lockout circuit governed by the lockout relays FSA and BSA, and which lockout circuit becomes effective to supply steady orr4 non-coded current to the track rails of one section when trackway energy from that section leaks forwardly over a defectivejoint into the track rails of the other adjacent section. This steady energy, feeding over the faulty joint, then continuously energizes the code following relay of the advance section, and causes the decoding apparatus `to control the associated signal to display its restrictive indication to thereby indicate the faulty condition of the insulated joint. The manner in which this protection is established by th apparatus of Fig. 3 will be explained in more detail hereinafter.

The track sections of Fig. 3 are further provided with front and back contact code following relays f the type previously shown and described in connectionwith Fig. 2, the code following relays associated with section 3 4 only being shown in the diagram. One relay DR2a is located at cut-section location 3a to cascade the trackway energy from subsection` 3 3a into the subsection 311-4, in a manner to be made clear presently. The other relay DRZ of Fig. 3 is located adjacent the entrance end of section 3 4, and controls relays H4 and AJ4 to thereby selectively control the aspect displayed by signal S4, and the supply of trackway energy to the section next in the rear of section 3 4. Relay DR2 of Fig. 3, as shown, further controls the two lockout relays FSA and BSA.

Relay FSA is controlled by the first or ,front contact" output winding I4 of relay DB2, through the medium of rectifier R3, which has its input terminals connected across the terminals of winding I4 of relay DB2, and has its output terminals connected across the terminals of relay FSA, which relay also has a short-circuiting resistor 26 connected across its terminals to provide the relay with slow releasing characteristics. The output terminals of rectifier R3 also are connected to the primary winding I6 of decoding transformer DTI, whereby control of relays H4 and AJ4 is established in the manner previously explained in detail in connection with the description of the apparatus of Fig. 1. However, the circuit whereby rectiiier R4 (which supplies current to relay H4) is energized from secondary winding I'I of transformer DTI, now includes front contact 21 of relay BSA.

Relay BSA is controlled by the second or back contact output winding 23 of relay DR2 through the medium of a rectier R1, which has its input terminals connected across the terminals of winding 23 of relay DR2 and has its output terminals connected with the terminals of relay BSA over a circuit which includes front contact 28 of relay FSA. Relay BSA also has a shortcircuiting resistor 29 connected across its terminals over a circuit including front contact 28 of relay FSA, so that when contact 28 is closed the resistor is effective to render relay BSA slow to release.

The supply of trackway energy to the track rails of the section next in the rear of section 3 4 is now controlled by relays H4, FSA and BSA. Trackway energy of code is supplied to the rear section over a circuit passing from terminal BX through contact |80 of coder CT4, front contact 6 of relay H4, front contact 30 of the primary of transformer TT4 to terminal CX.

from terminal BX through back contact 32 ofl relay BSA, front contact 3| of relay FSA and the primary of transformer 'I'I4 to terminal CX.

The operation of the apparatus located at ythe entrance end 4 of section 3-4 of Fig. 3 is as fol- I lows: when 180 code is supplied to the control winding I 5 of relay DR2 from the track rails of section 3-4, the current impulses induced in front contact output winding I4 of relay DR2 effectively energizes and picks up relay FSA, which relay is held up during the oi period of such impulses by virtue of its slow releasing characteristics. The coded current induced in winding I4 of relay DR2 also energizes the primary winding of transformer DTI, whereupon relay AJ4 becomes effectively energized and picks up. With relay FSA picked up to close its front contact 23, the circuit for relay BSA is completed whereby the impulses of current induced in back contact winding 23 of relay DR2 are eil'ective to pick up relay BSA, which relay is held picked up during the o period of such induced impulses by virtue of its slow releasing characteristics. Relay BSA in picking up closes its front contact 21 to complete at that point the circuit for relay H4 whereupon relay H4 also picks up in response to the energization of decoding transformer DTI, to close its front contact I9 and thereby cause (front contact 20 of relay AJ4 being closed) signal S4 to display its proceed indication. Front contact 6 of relay H4 also is closed, whereupon 180 code is supplied to the rear section over the circuit previously traced.

When 75 code is supplied to relay DR2, relay AJ4 becomes released by virtue of the functioning of its decoding unit DU-I80, but relays FSA, BSA and H4 remain picked up. Signal S4 now is caused to display its caution indication, and 180 code is supplied to the rear section.

When section 3-4 is occupied so that no trackway energy is supplied to relay DR2, the energy induced in front contact winding I4 of relay DR2 then is insufliclent to eectively energize relay FSA, so that relay FSA is released and opens its front contact 28 to thereby open the circuit for relay BSA, with the result that relay BSA also is released. With relays FSA and BSA released.-75 code 'is supplied to the rear track section. Furthermore, since the current induced in front contact winding I4 of relay DR2 and supplied to decoding transformer DTI is at its minimum value and is not coded, relays H4 and AJ4 are released, to cause signal S4 to display its stop indication.

Theapparatus located at the entrance end of section 3 4 of Fig. 3 further functions to prevent, in the event of a broken-down insulated joint, the display of a false proceed indication of signal S4, which false indication might be caused by the broken-down insulated joint in the following manner. Assume that under the conditions last described (section 3-4 occupied and '75 code being supplied to the rear lsection) an insulated joint separating the rails of the two sections breaks down due to the passage of the train through section 3 -4. If, for exam the Joint 2 located in rail I at the entrance end 4 of section 3 4 breaks down, the '75 code energy supplied to the rear section will leak forwardly over the defective joint into rail I of section 3 4, and after the train has passed far enough into section 3-4 so that a material length of the track rails is included in the train shunt for relay DR2, relay DR2 might be energized by this current leaking over the defective insulated joint, since section, and in picking up relay H4 would control l the trackway energy supplied to the rear section so that 180 code then would be supplied to the latter section. This 180 code, in leaking forward over the insulated joint, then might cause relay DR2 to effect the pick-up of both relays H4 and AJ4, thereby establishing the proceed indication of signal S4 even though the section 3-4 is occupied, thereby causing signal S4 to display a false proceed" indication.

'I'he above mentioned operation, which might cause signal S4 to display a false proceed indication, is prevented by the lockout circuit controlled by relays FSA and BSA in the following manner. When relay DR2 becomes energized during the onperiod of the first impulse of 75 code leaking over the defective insulated joint, the energy induced in front contact output Winding I4 of relay DR2 energizes and picks up relay FSA. With relay FSA picked up the lockout circuit previously referred to is completed over its front contact 3l and back 32 of relay BSA, whereupon steady energy is fed into the rear section. This steady energy, feeding over the defective insulated joint, continuously energizes relay DR2 with the result that energy is continually induced in front contact output winding I4 or relay DR2, and relay FSA consequently is held energized to maintain the lockout circuit. Relay BSA remains released, since the current induced in back contact winding 23 of relay DR2 is at its minimum value as the result of the energization by the steady lockout energy of control winding I5 of relay DR2. open at its front contact 21 the circuit for relay H4, and with decoding transformer DTI now provided with steady or non-coded unidirectional current, relays AJ4 and H4 also are released to control signal S4 to its restrictive or stop" indication. From the foregoing it follows, therefore, that when an insulated joint separating two adjacent track sections breaks down, the signal located adjacent the defective joint is caused to display its restrictive indication to indicate the defective condition of the joint.

f In the event that an insulated joint separating two sections breaks down when the section in advance of section 3.-4 is unoccupied, the lockout circuit previously described then becomes eil'ective to control the associated signal to its restrictive indication. If,` under the above conditions, both section 3-4 and the section in the rear of section 3-4 are .supplied with 180 code, the coders supplying each of the above mentioned sections will be arranged so that the code impulses supplied to one section are out of step with With relay BSA released to the impulses supplied to the other. Then, if a joint fails and becomes ineffective to insulate a rail of section 3 4 from the section next in the rear, the code following relay DR2 of section 3 4 will be supplied with impulses having a longer on period (due tothe code impulses being out of step) than off period. As a result, front contact winding I4 of code following relay DR2 will have induced therein relatively long impulses of energy which will energize and pick up the associated FSA relay, but the shorter impulses induced in back contact winding 23 of relay DR2 will be ineiective to effectively enerthe entrance end of section 3 4.

gize relay BSA, whereupon the latter relay releases to establish the lockout circuit. The steady energy of the latter circuit then will feed over the defective jointmvhereupon relays AJ4 and H4 release to control signal S4 to its stop indication.

Furthermore, in the event that an insulated joint fails when both section 3 4 and its adjoining r'ear section are unoccupied and section 3 4 is supplied with '15 code, the 180 code feeding from the rear section into the rails of section 3 4 over the defective joint then will be out of step with the 75 code in section 3 4, whereby the longer impulses supplied to code following relay DR2 will cause the associated relay FSA to remain picked up, and the associated relay BSA to release, in the manner previously explained. The associated signal then will be controlled to its restrictive position.

Relay DR2a, previously referred to as being located at cut-section location 3a of Fig. 3 to cascade the trackway energy from advance subsection 3 3a into rear subsection 3a 4, is provided with a slow releasing lockout relay BSA I which it controls to prevent cascading of the steady lockout energy. The relay DR2a has its "front contact output winding I4 connected across the track rails I and Ia of subsection 3a- 4 over a circuit including front contact 34 of relay BSA-I, and its control winding I 5 is supplied with energy from the track rails of subsection 3 3a through the medium of resonant rectifier unit RUIa. The back contact winding 23 of relay DR2a is connected to the lockout relay BSA I through a rectifier R1. In operation, as long as coded trackway energy is supplied from subsection 3 3a to relay DR2a, the trackway energy is reproduced in kind by relay DRZa and is supplied by that relay to subsection 3a 4 over its output windingl I4. That is, relay BSA I is energized and picked up to close its front contact 34 during the oil period of'the code, and relay BSA I is held picked up during the on period of the code because of its slow releasing characteristics. With front contact 34 of relay BSA 'I closed, winding I4 of relay DRZa then is connected across the track rails of section 311-4 so that the impulses of energy induced in such wind ing during the on period of the code are supplied to the section 3a 4. However, when section 3 3a is occupied so that trackway energy is shunted away from control winding I5 of relay DRa, relay BSA I then is continuously energized to connect winding I4 across section 3a 4, but the` energy induced in output winding I4 at this time is at its minimum value so that the voltage of the trackway energy now supplied to the track rails of section 3a 4 is insuiiicient to operate the code following relay DR2 located at In the event that an insulated joint separating section 3 4 from the section in advancek breaks thereby disconnect output winding I4 of relay l DR2a from the track rails of subsection 3a-4. It is apparent, therefore, that when relay DR2a is continuously energized, the rails of subsection 3a 4 are not supplied with trackway energy, with the result that the steady or non-coded lockout energy supplied to advance subsection 3 3a is not cascaded around cut-section location 3a into the rear subsection 3a 4. The effect of disconnecting winding I4 of relay DR2a from subsection 3a 4 when non-coded lockout energy is applied to the rails of subsection 3 3a is that relay DRZ, located at the entrance end of section 3 4, causes its associated signal to displaygts stop indication, and also causes the section in the rear of section 3 4 to be supplied with 75 code. As a result, it is obvious that relay DR2a prevents the non-coded lockout energy from being cascaded around the cut-section location, and causes the two signals next in the rear to display respectively stop and "caution, the other signals further in the system not being effected by the lockout energy supplied to subsection 3 3a.

Fig. 4 shows another manner iniwhich track- Way energy from one subsection may be cascaded into an adjacent subsection by a saturation relay without permitting cascading of the noncoded lockout energy. Referring now to Fig. 4, the relay DR3 shown at the cut-section' 3a of Fig. 4 is, in general, constructed similarly to relays DRI and DR2 previously described. However, the core leg I2 of relay DR3 is separated by air gaps 35 from the rest of the core structure, and in addition no output winding need be mounted on this leg. The control winding I5 of relay DR3 is supplied with energy from the track rails of subsection 3 3a, and back contact" output winding 23 of relay DR3 is connected directly across the track rails of subsection 3a 4. When winding I5 is supplied with coded current from subsection 3 3a, legs 9 and I0 of relay DR3 become saturated to circulate the flux created by input winding I3 of that relay through the air gaps 35 so that the primary flux circulates through leg I2, and the energy induced in winding 23 of relay DR3 is at its minimum value. However, during the oil period of the code, the primary ilux is then circulated through core legs 9 and I0 because of the high reluctance of air gaps 35, thereby inducing energy in winding 23,

which energy then is supplied to subsection 3ft-4 p to thereby cascade trackway energy from the one subsection to the other. In the event that the apparatus located in advance of cut-section location 3a is functioning to supply the rails of subsection 3 3a, with non-coded lockout energy because of a failed insulated joint at signal location 3, the nonecoded energy impressed upon control winding I5 of relay DR3 saturates legs 9 and IU so that the output of winding 23 is at its minimum value. The non-coded lockout energy therefore will not be cascaded around location 3a, but rather the rails of' subsection 3ra-4 will be deenergized (as if a train were in subsection 3a-4) to cause the apparatus located in signal location 4 to control signal S4 to its restrictive indication, and also to supply 75 code to the rails of the section next in the rear of section 3-4. It follows from the foregoing, therefore, that with relay DR3 constructed in the manner described, such relay located at location 3a will cause the trackway energy of one subsection to be cascaded into the other subsec tion only in the event that the advance subsection of the two is supplied with coded energy.

Relay DR3 further functions to clear out subsection 3a4 when a train vacates that portion of section 3 4, by supplying to that subsection steady or non-coded clearing out energy. That is, when a train operating over section 3-4 vacates subsection3pf--4 and occupies subsection 3-3a, the train then shunts control winding I5 of relay DR3 located at cut-section loca# tion 3a. The control winding of relay DR3 being deenergized, the energy induced in output winding 23 of that relay is then at its maximum value, so that steady or non-coded clearing out energy is supplied to subsection 3a-4. Thus, when subsection 3a-4 is occupied, the apparatus located at the entrance end of section 3-4 is shunted and is deenergized to control signal S4 to its restrictive indication. When subsection 3a4 becomes vacated and subsection 3-3a is occupied, then the apparatus located at the entrance end of section 3-4 is supplied with steady non-coded energy, and signal S4 remains at its restrictive indication by virtue of the effect of the non-coded energy on the code following relay and decoding transformer for that section. This steady energy supplied to the rails of subsection 3af-4 now may be utilized to control any apparatus which is desired to be controlled to one condition or the other in accordance withtrafflc conditions only in subsection 311-4. For example, the cut-section in section 3-4 may be located at a highway crossing, which may be protected by any of the well-known protective devices. Under the above conditions, it is desirable to so control such devices as to effect their operation as long as subsection 3af--4 is occupied and the train is approaching or occupies the intersection, but that after the train clears the intersection, then ythe protective devices will be controlled to their normal inoperative condition. The steady non-coded energy supplied by relay DR3 to subsection 30,-4 when subsection 3-3a is occupied thus may be utilized by apparatus (not shown) to so control the apparatus controlling the protective devices.

With apparatus of the type of relay DR3 located at the cut-section location 3a in section 3 4, the apparatus located at the signal location 4 in the rear of that cut-section must be arranged so as to not cascade the non-coded clearing out energy from one section to the next, and one form of apparatus providing broken-down insulated joint protection at the signal location 4, but preventing the cascading of steady noncoded energy at that point is shown in Fig. 4. As can be seen from an inspection of Fig. 4, the apparatus located at signal location 4 is substantially similar to the apparatus located at signal location 4 of Fig. 3, except that in Fig. 4 a slow acting two winding relay J-FSA replaces the single winding relay FSA of Fig. 3.

The decoding transformer DTIa shown in Fig. 4 is provided with two secondary windings one of which, winding I1, controls the code detecting relay H4 in the manner previously explained in detail in connection with Fig. 3, and the other of which, winding I8, controls the rst or pickup winding 52 of relay .1 -FSA. When relay J-FSA is released, its other winding 53 is shortcircuited over its back contact 35, so that relay J-FSA is made slow in picking up, and will not4 pick up on the first impulse of energy supplied to its winding 52. That is to say, the two windy ings 52 and 53 of relay J-FSA are so arranged that when both windings are supplied with unidirectional current of similar polarity, the two windings act cumulatively to create flux which tends to pick up the tractive armature of the relay: If, however, relay J-FSA is released so that winding 53 is short-circuited, and a single current impulse is supplied to winding 52, the building up of the magnetic flux created thereby induces an electromotive force in the short-circuited winding 53 of the relay which opposes the action of the ux created by winding 52, and as a result the armature oi.' relay J-FSA is retained in its released position. If winding 52 of relay J-FSA isl supplied with successive current lmpulses, however, the energy level required to pick up the armature of relay J-FSA is built up in the relay by virtue of the action of the shortcircuited winding 53, which functions to maintain a substantial energy level in relayJ-FSA during the "oi period of the impulses supplied to winding 52 (due to the electromotive force created in winding 53 by the decaying flux of winding 52) so that each successive impulse supplied to winding 52 increases the energy level of the relay until its pick-up energy level is reached. Relay J-FSA preferably is proportioned to pick up onthe second or third successive impulse supplied to its winding 52, and when relay J-FSA picks up, front contact 31 is closed to enable additional energy to be supplied to the relay to prevent the relay armature from alternately picking up and releasing in response to the impulses supplied to its windings by relay DR2. This additional energy is supplied to relay J-FSA by energizing winding 53 of relay J-FSA, which winding is energized over a stick circuit which may be traced from the lower output terminal of rectifier R3 through back contact 38 of relay H4 or front contact 39 of relay BSA, front contact 31 of relay J-FSA and winding 53 of relay J-FSA to the upper output terminal of rectifier R3. When both windings 52 and 53 are energized by current impulses, the energy level set up in relay J-FSA is then sufficient to maintain its armature picked up during the off period of such impulses. The remainder of the apparatus of Fig. 4 is substantially similar to the apparatus of Fig. 3.

The apparatus located at signal location 4 of Fig. 4 operates in the following manner. When relay DR2 is supplied with coded energy from the rails of subsection 3a-4 of Fig. 4, primary winding I6 of transformer DTIa is intermittently energized to induce energy in its two secondary windings. Relay J-FSA then picks up on the second or third current impulse induced in secondary winding I8 of decoding transformer DTIG, and closes its front contacts 31 and 28a whereby the relay is maintained picked up by virtue of the additional energy supplied to its second winding 53. With front contact 28a of relay J-FSA closed, relay BSA also picks up to close its front contact 21 whereupon relay H4 likewise picks up. Relay AJ4 will be picked up or released according as relay DR2 is supplied with 180 or 'I5 code, as explained heretofore.

If, now, subsection 3a-4 is occupied so that control winding I5 of relay DR2 is deenergized, then relays J-FSA, BSA, H4 and AJ 4 will be re- Vcontrol winding I of relay DB2 responds to the pulse induced in secondary winding I8 of decod` ing transformer D'I'Ia, thereby completing over its front contact Bla the lockout circuit, which.

now supplies steady or non-coded lockout energy to the rear section. Steady current induced in output winding I4 of relay DB2 in response to the steady lockout. energy (which feeds over the defective joint) is then supplied to winding 53 of relay J-FSA over the stick circuit previously traced. This circuit now includes its own front contact 31 and back contact 38 of relay H4, so that relay J--FSA is 4held energized to hold the lockout circuit completed. Relay BSA will be released because of the uncoded current of relatively low magnitude induced in back contact" output winding 230i relay DB2 when relay DB2 is constantly energized by the lockout energy, and relays H4 and AJ4 also will be released since decoding transformer DfIIa is now supplied with uncoded unidirectional current. It is readily apparent, therefore, that the apparatus of Fig. 4 functions to control signal S4 to its restrictive indication in the event of a broken-down insulated joint at signal location 4, much in the manner previously explained in connection with the apparatus of Fig. 3.

However, in the event that control winding I5 of relay DB2 is deenergized (as for example in the event that a train occupies subsection 3a-4 and thereby shunts the trackway energy away from control winding I5), then relays J-FSA, BSA, H4 and AJ4 are released. When the train vacates subsection 3a-4 and relay DB3 supplies steady or non-coded clearing out energy to subsection 3d-4, this clearing out energy will not be cascaded around signal location 4. That is to say, steady energy supplied to subsection 3af-4 will cause output winding I4 of relay DB2 to be continuously energized. 'I'his energy supplied to decoding transformer D'IIa will send a first impulse to relay J-FSA during the building up of flux in the transformenbut after the flux has been built up no further energy transfer between the .primary and secondary windings of transformer D'IIa will be effected since the primary winding of transformer DTIa is now supplied with uncoded unidirectional current. Relay .1 -FSA, as pointed out previously, will not be picked up on the first impulse supplied from the transformer DTIa since back contact 36 of relay J-FSA is closed to complete the shunt upon winding 53 and as a result relay J-FSA remains released when relay DB2 is supplied with non-coded clearing out current. Relays BSA, H4 and AJ4 also will remain released since relay J--FSA is released and since decoding transformer DTIa now is supplied with uncoded unidirectional energy, so that signal S4 is controlled to its restrictive indication and the section in the rear of section 3 4 is supplied with 75 code. It follows from the foregoing that the apparatus located at signal location 4 of Fig. 4 provides broken-down insulated joint protection at` that location in the usual manner, but does not cascade non-coded energy from section 3-4 to the section in the rear. As was pointed out heretofore,y the uncoded current induced in output winding I4 of relay DB2 when subsection 3ft-4 is supplied with clearing out energy may be j employed to control apparatus (not shown) which Y -traine conditions is desired to be responsive to only in subsection 3ra-4.

Referring now to Fig. 5, I have herein represented a modification of the cut-section facilities located at cut-section 3a in Fig. 4. In this modiflcation of Fig. 4, an improved form of back contact code following saturation relay DB4 replaces the back contact saturation relay DB3 shown in Fig. 4. The relay DB4 shown in Fig. 5 and relay DB5 hereinafter referred to and shown in Fig. 6, are both improved forms of saturable transformer type relays of the class disclosed in a copending application Serial No. 280,997, filed on June 24, 1939 by Bernard E. `OHagan for Railway signaling apparatus, and certain features of the structures shown in Figs. 5 and 6 and described in this application are broadly covered in the said copending application. Other features of relay DB4 shown inyFig. 5 of the present application are coveredV by claimsin another copeneding application for Letters Patent, Serial No. 281,373, led on June 27,y 1939 by Bernard E.

OHagan for Railway signaling apparatus.

Relay DB4, as shown in Fig. 5, is substantially similar' in construction to the relays DRI and DB2 previously described, except that the magnetizable core of relay DR4 is provided with ve integral legs 9, III, II, I2 and I2a, respectively, connected together at each end to form an integral relay core structure. The control winding I5 of relay DB4 now comprises four coils one mounted on each of the legs of the core, except the leg` I I upon which is mounted the local input winding I3 of the relay. The pairsV of the saturation coils mounted on either side of the input windingV are connected in series in such manner that the flux created by current supplied to the coils circulates through the closed path provided by the two legs upon which each pair of the output windings is mounted. Relay DB4 also has "back contact output Winding 23 mounted on legs I2 and I2a of the core and has mounted on legs 9 and I0 a biasing winding 42 comprising two coils 42a, and 42h, connected in series in such manner that when supplied with current from a direct current source, the flux created by such current opposes and substantially balances the flux created by coils I5a. and lib of the control winding, thereby in effect nullifying the action of the latter coils in saturating the legs 9 and I0 of the relay. The direct current source for the biasing winding 42 of relay DB4 may bea separate source of current, or may comprise as shown a secondary winding 43, mounted on leg II of relay DB4 and inductively coupled with input winding I3 of relay DB4 to supply current to biasing winding 42 through the medium of a rectifier B8.

In operation, control winding l5 of relay DBI is connected across the track rails of the advance subsection through the medium of resonant transformer unit BUIa, and output winding 23 of relay DB4 is connected directly' across the track rails of the rear subsection. When coded current is received by control winding I5 from they rails of the advance subsection, legs I2 and I2a of the relay become saturated by virtue of the flux supplied thereto by coils lic and I5d of the saturating winding, 'but the flux created by the coils I5a. and I5b and supplied to legs 9 and Ill is opposed and nullified by the flux created by biasing windings 42a and 42h so that legs 9 and I0 have relatively little reluctance. The primary flux created by input winding I3 thus will circulate through legs 9 and IU, with the result that practically no current is induced in output winding 23 of relay DR4 at this time. However, during the olf period of the code, the control winding I5 becomes deenergized and biasing winding 42 then saturates legs 9 and I0 so that the primary iiux is then circulated through legs I2 and I 2a, whereby an electromotive force of relatively large magnitude is induced in output winding 23 of relay DR4 during the off period of the code.

From the foregoing it is readily apparent that when non-coded lockout energy is present in the rails of the advance subsection, the constant energization of control winding I5 of relay DR4 will'result in the minimum energy being induced in back contact winding 23 of relay DRA so that the non-coded lockout energy is not cascaded around cut-section location 3a. Furthermore, with the advance subsection occupied, it can be seen that control winding I5 of relay DR4 then will be deenergized whereby maximum energy then is constantly induced in output winding 23 and is supplied to the rails of the rear subsection, thereby supplying to that subsection the clearing out energy previously mentioned.

In' addition, it should be pointed out that the construction above set forth for relay DR4 greatly increases the amplification ratio of the relay. That is, the ratio of the voltage induced in output winding 23 when control winding I5 of the relay is energized to the voltage induced in output winding 23 when control winding I5 is deenergized, is greatly increased. This increase in amplification is effected in part by providing portions of the control winding on each magnetic path of the primary ux of the relay, and by providing a biasing winding which functions under one condition of the control winding to saturate the one path on which it is mounted, and under the other condition of the control winding to nullify the ux created by the portion of the control winding mounted on that path. As pointed out previously, when control winding I5 of relay DR4 is deenergized, the constant energization of biasing winding 42 of relay DR4 saturates legs 9 and I Il, thereby forcing the primary flux through legs I2 and I2a upon which is mounted output winding 23. Energy of relatively high magnitude is therefore induced in winding 23. of relay DR4 is energized. the ux created in legs 9 and I0 by the control winding coils I5a and I 5b is opposed and nullii'led by the flux created by biasing winding 42, while legs I2 and I2a become saturated by virtue of the control winding coils |50 and I5d mounted thereon. The primary flux thus is forced through legs 9 and I0 because of its lower reluctance, and consequently substantially no energy is induced in winding 23. Output winding 23 of relay DRA therefore has approximately the same characteristics as a back contact of a tractive armature type relay.

In Fig. 6 the` apparatus located in signal location V4 is substantially similar to the apparatus shown at location 4 in Fig. 3, except that the relay DR2 of Fig. 3 is now replaced with relay DR5, and decoding transformer IYII of Fig. 3 also is replaced by another decoding transformer DT4. Referring now to Fig. 6. the saturation relay DR5 here shown is substantially similar to relay DR4 of Fig. 5 previously described, except that relay DR5 is provided with a "front contact output winding I4, which comprises two coils I4a and I4b mounted respectively on When, however, control winding I5.

legs I2 and I2a of relay DR5 and connected in series in such manner that any voltages induced therein by the primary iiux of winding I3 are additive. A biasing winding 44 of relay DR5, as shown, comprises two coils 44a and l4417 connected in series and disposed respectively on legs I2 .and I2a. Winding 44 is energized from a direct current source indicated by the terminals B and C.

The operation of relay DR5 is substantially similar to the operation previously described for relay DR4, with winding I4 now functioning as a front contact output winding. That is, when control winding I5 of relay DR5 is energized (as for example during the on period of the code) the fluxy created by the control winding in legs I2 and I2a is opposed and nullied by the flux created by the biasing Winding 42. At the same time legs 9 and I0 are saturated by the current flowing in control winding coils I5a and I5b so that the primary flux circulates through legs I2 and I2a to induce energy in output winding I4 which is mounted on legs I2 and I2a, while practically no energy is induced by such flux in output winding 23 disposed on legs 9 and I0. When, however, winding I5 is deenergized (as for example during the off period of the code) then legs I2 and I2a are saturated by virtue of the flux supplied' thereto4 by biasing winding 44, so that the primary ux then is circulated through legs 9 and I0, whereby energy is induced by such ux in output winding 23 and substantially no energy is induced in output winding I4. In this form of relay, output winding 23 therefore corresponds to a back contact" output winding and output winding I4 corre; sponds to a front contact output winding.

The decoding transformer DT4 shown in Fig. 6 is similar to the decoding transformer disclosed and claimed in a copendng application for Letters Patent, Serial No. 213,016, led on June 10, 1938, by BernardE. OHagan for Railway traffic controlling apparatus. Transformer DT4 comprises a core 45 provided with a primary winding 46 which is connected to the output terminals of rectifier R1 (which has its input terminals connected with back contact output winding 23 of relay DR5) and a core 41 provided with a primary winding 48 which is connected with the output terminals of rectifier R3 l(which in turn has its input terminals connected with front contact output Winding I4.of relay DR5) This transformer also comprises two secondary windings 49 and 50 which link both cores 45 and 41, and which secondary windings are connected respectively with the input terminals of rectifier R4 and the input terminals of decodingrunit DTI-|90. The primary windings 46 and 48 are so arranged that the unidirectional fluxes which are set up in thecores 45 and 41 when current is being supplied to these windings will thread the secondary windings in opposite directions, and in order to cause the flux to decay quickly inthe cores 45 and 41 when the associated primary windings become deenergized in spite of the short-circuiting action of rectifiers R1 and R3, each core is provided with one or more air gaps 5I, or their equivalent, two such air gaps being shown in the drawings because of the greater ease of assembly of the transformer which is 'affordedby this arrangement.

With decoding transformer DT4 constructed and arranged in this manner, it will be apparent that when code following relay DR5 is being supplied with coded energy from the rails of section 3 4, the primary windings of the de coding transformer will be alternately supplied with impulses of unidirectional current and will set up in the cores 45 and 41 unidirectional fluxes which in turn will induce alternating current in both secondary windings 4 9 and 50. It will also be apparent that due to the fact that the cores 45 and 41 have relatively high reluctance and the further fact that the fluxes set up in these cores always thread these cores in the same direction, the rate of growth and decay of the fluxes in .these two cores will be very rapid, whereby the eciency and operation of the decoding apparatus as a whole is materially improved.

As can be seen from an inspection of Fig. 6, the output windings I4 and 23 of relay DRE control respectively the FSA and BSA relays in substantially the same manner as `was pointed out in connection with Fig. 3, and it is believed that the manner in which the apparatus of Fig. 6 functions to control signal S4 and the supply of trackway energy to the track section in the shown in Fig. 1, which are incorporated into a signaling system employing at the signal location a code following relay ofthe tractive armature type to control the `operation of signal `S4 and the lockout means protecting against brokendown insulated joints.

Referring'now to Fig, 7, relay DRla there shown located at cut-section 3a is substantially similar to the relay DRIa shown in Fig. 1. In

Fig. 7, however, the control winding I5 of relayI DRIa is supplied with energy from the track rails of the advance subsection 3-3a through the medium of resonant rectifier unit RUI a.

The apparatus shown in Fig. 'l located at signal location 4 forms no part of my present invention and in the well-known form here shown comprises a code following relay TR of the tractive armature type, connected across the track rails of subsection 311-4, which relay controls the signal control relay AJ 4 through the medium of a decoding transformer DT5, and the signal control relay H4 and the two lockout relays FSA and BSA over its code following relay contacts. That is, relay FSA is controlled over a front contact 55 of relayv TR`; relay BSA is controlled over a back contact 56 of relay TR and front contact28 of relay FSA; and relay H4 is picked up over a circuit including front contact 55 of relay IR, its own back contact 51, and front contact 21 of relay BSA. VRelay H4 also is provided with a stick circuit including its own front contact 58 and front contact 21 of relay BSA. Relay A34 is controlled by current from transformer DT5 through the medium of its decoding unit DU |80; and the decoding transformer DTS has a portion of its primary winding supplied with energy over a front contact V5!! of relay TR, the

remainder of its primary being supplied with is readily apparent from an inspection of the drawings.

From the foregoing,` it is apparent that the signaling ,system of Fig:\7 employs at the signal location a code responsive relay of the tractive armature type to control the associated signal and the supply of energy to the section in the rear of section 3 4. At the cut-section location of the section, however, a code responsive relay of the saturation type is located to cascade the trackway energy from the advance subsection into the rear subsection, whereby the trackway energy is cascaded from one subsection into its adjoining subsection by means of a code following relay which has no moving parts.

It should be pointed out that while relays DRI, DB2, DB4 and DRE are herein shown having but a single front contact output winding, additional output windings may be provided for and arranged on such relays to provide as many front contact output windings as is desired. Similarly, although relays DRE, DB3, DR4 and DRS are herein `shown having but a single "back contact" output winding, additional output windings may be provided for such relays and arranged to provide as manyfback contact output windings for such relays as is desired;

y Although I have herein shown and described only a few forms of railway signaling apparatus embodying my inventionVit is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination with adjoining advance and rear sections of railway trackelectrically separated from each other by insulated rail joints, means for supplying the track rails of said advance section with trackway energy which is coded at a first rate under certain conditions and is coded at a second rate under others, a code following relay all of the component parts of which are stationary and comprising a magnetizable core provided with a primary winding constantly supplied withalternating current and two secondary windings inductively coupled with said primary winding, said relay also including a saturation winding receiving energy from the track rails of said advance section and disposed on said core in such manner as to be eiective to control the inductive coupling of said relay primary and secondary windings to cause impulses of energy to be alternately induced in each secondary winding having a code frequency corresponding to the code frequency of the energy supplied to said relay saturation winding, a signal for governing traiiic in said section, means governed solely by the impulses of energy induced in a particular one of said relay secondary windings for selectively controlling said signal in accordance with the frequency at whichsuch en ergy is coded, and means governed by the irnpulses of energy induced in each of said two relay secondary windings for supplying the rails of said rear section with trackway energy which is normally coded but which is steady or uncoded in the event that energy feeds over said insulated rail joints from said rear section into said advance section to falsely energize the saturation winding of the code following relay of said advance section. Y

2.-In combination with adjoining advance and rear sections of railway track electrically separated from each other by insulated rail joints, means for supplying the track rails of said advance section with trackway energy coded at a first rate under certain conditions and at a second rate under others, a code following relay of the saturation type comprising a magnetzable core having a saturation winding supplied with energy from the rails of said advance section, said relay having a primary windingdisposed on said core and constantly supplied with alternating current, said relay also having two secondary windings disposed on said core and inductively coupled with said primary winding in such manner that a relatively high electromotive force is induced in one secondary winding or the other according as said saturation relay is or is not supplied with energy whereby when coded energy is supplied to said saturation winding there will be induced in each secondary winding impulses of energy having a code frequency corresponding to the code frequency of said coded trackway energy, a signal for governing traiiic in said advance section, means controlled solely by said impulses of energy induced in a particular one of said relay secondary windings for selectively controlling said signal in accordance with the code frequency of said induced energy, and means controlled by the impulses of current induced in each -of said relay secondary windings for supplying the rails of said rear section with trackway energy which is normally coded but which is steady or uncoded in the event that energy feeds forward over said insulated rail joints from said rear section into said advance section to falsely cause the energization of the saturation winding of the code following relay of said advance section.

3. In combination, a section of railway track electrically separated from adjoining advance and rear sections by insulated rail joints, said section being divided by insulated rail joints into adjoining -advance and rear subsections, means for supplying coded trackway energy to the track rails of said advance subsection, a code responsive relay of the saturation type having a magnetizable core provided with a primary winding constantly supplied with periodically varying current, said relay having a secondary winding disposed on said core and inductively coupled with said primary winding, said relay also hav- 'ing a saturation winding disposed on said core and receiving energy from the track rails of said advance subsection to vary the inductive coupling of said relay primary and secondary windings in step with supply of energy from the rails of said advance subsection, means for connecting said relay secondary winding across the track rails of said rear subsection whereby the trackway energy of said advance subsection is cascaded into said rear subsection, a code responsive control relay for said section receiving energy from the track rails of said rear subsection, railway trafc controlling apparatus governed by said code responsive control relay, and means controlled by said code responsive control relay for supplying the track rails of the adjoining rear section with trackway energy which is normally coded but which is steady or uncoded in the event that energy feeds over said insulated rail joints from the adjoining rear section into said advance section to falsely energize said code responsive control relay for said section.

4. In a railway signaling system, in combination, a stretch of railway track divided into adjoining advance and rear sections which are electrically separated from each other by insulated rail joints, means for supplying coded trackway energy to the rails of said advance section, a saturation relay having a magnetizable core carrying a saturation winding supplied with venergy from the track rails of said advance section, said core carrying a primary winding constantly supplied with energy` from a source of alternating current, said core also carrying two secondary windings inductively associated with said primary Winding in such manner that a relatively high electromotive force is induced in one of said secondary windings or the other according as said saturation winding is or is not supplied with energy, a ilrst and a second slow release relay, circuit means for energizing said rst slow release relay and effective on the supply of energy from said one secondary winding, circuit means including a front contact of said first slow release relay for energizing said second slow release relay and effective on the supply of energy from said other secondary winding, a source of energy for the track rails of said rear section, two coding contacts, circuit means for connecting said source of energy to the track rails of said rear section over one of said coding contacts or the other according as said first and second slow release relays are both picked-up or are both released, and a circuit including a front contact of said first slow release relay and a back contact of said second slow release relay for connecting said source of energy directly to the track rails of said rear section in the event that energy feeds over the insulated rail joints from the rear section into the advance section.

5. In combination with adjoining advance and rear sections of railway track which are electrically separated by insulated rail joints, means for supplying coded current to the rails of said advance section, a saturation relay all of the component parts of which are stationary and comprising a magnetizable core carrying a saturation winding supplied with direct current from the track rails of said advance section in response to said coded current, said core carrying a primary winding constantly supplied with current from an alternating current source, and said core also carrying two secondary windings inductively coupled with said primary winding in such manner that a relatively high voltage is induced in one of said secondary windings or the -other according as said saturation winding is or is not supplied with direct current, a rst and a second slow release relay, circuit means for energizing said rst slow release relay in response to the relatively high voltage induced in said one secondary winding of said saturation relay, circuit means including a front contactV of said first slow release relay for energizing said second slow release relay in response to the relatively high voltage induced in said other secondary winding of said saturation relay, a source of energizing current for the track rails of said rear section, two coding contacts, circuit means for connecting said source of current to the track rails of said rear section over one of said coding contacts or the other according as said first and second slow release relays are both picked up or are both released, and a circuit'including a front contact of said rst slow release relay and a back contact of said second slow release relay for connecting said energizing source directly to the track rails of said rear section in the event that current feeds over said insulated rail joints from the rear section into the advance section.

6. In combination with adjoining advance and rear sections of railway track which are electrically separated'by insulated rail joints, means for supplying coded current to the rails of said advance section, amagnetizable core providedl with a primary winding and a saturation winding and two secondary windings inductively coupled with said primary winding in such manner that if said primary winding is supplied with alterhating current a relatively high voltage will be induced vin one of said secondary windings or the other according as said saturation winding is or is not supplied with unidirectional current, means for constantly supplying said primary winding with alternating current, means for supplying said saturation winding with unidirectional current from the rails of said advance section in response to said coded current, a ilrst slow release relay, means for energizing said first slow release relay whenever the relatively high voltage is induced in said one secondary winding, a second slow release relay, circuit means including a front contact of said iirst slow release relay for energizing said second slow release relay whenever the relatively high voltage is induced in said other secondary winding, a code detecting relay, circuit means including a front contact of said second slow release relay for energizing said code detecting relay whenever the relatively high voltage is induced in said one secondary winding, a signal positioned adjacent the junction of' said advance and rear sections, a control circuit for said signal governed by said code detecting relay and effective to operate said signal to a permissive or a restrictive indication according as said code detecting relay is picked up or released, a source of current for said rear section, two coding contacts, circuit means for connecting said source of Vcurrent with the track rails of said rear section over one of said coding contacts or the other according as said rst and second slow release relays are both picked up or are both released, and a circuit including a front contact of said iirst slow release relay and a back contact of said second slow release relay for connecting said source of current directly to the track rails of said rear section in the event that current feeds over said insulated rail joints from the rear track section into the advance section.

7. In combination, a section of railway track divided into an advance subsection and a rear subsection, means for supplying the track rails of said advance subsection with trackway current which is coded under certain conditions and is steady under others, a saturation relay comprising a magnetizable core provided with a primary winding and a saturation' winding and two secondary windings inductively coupled with said primary winding in such manner that if said pri; mary winding is supplied with alternating current a relatively high electromotive force will be induced in one oi said secondary windings or the other according as said saturation winding is or is not supplied with unidirectional current, means for constantly supplying said primary winding with alternating current, means for supplying unidirectional current from the track rails oi said advance subsection to said saturation winding in response to said trackway current, a second relay, means for energizing said second relay whenever the relatively high electromotive force is induced in said other secondary winding of said saturation relay, and means including a front contact of said second relay for connecting said one secondary winding of4 said saturation relay across the track rails' oi said rear subsection whereby the track rails of that subsection are supplied with current corresponding to the track` way current supplied to the track rails of said advance section when and only when Ithe trackway current supplied to the track rails of said advance section is coded.

8. In combination with adjoining advance and rear subsections, means for supplying the rails of said advance subsection with trackway energy which is coded under certain conditions and steady under others, a relay of the saturation type comprising a magnetizable core` carrying a saturation winding receiving energy from said advance subsection, said core carrying an input winding constantly connected with a source of alternating current, and said core also carrying two output windings inductively coupled with said input winding in such manner that a relatively high electromotive force is induced in one or the other of said two output windings according as said saturation winding is or is not energized, a second relay controlled .by the electromotive force induced in said other output winding of said saturation relay, and a circuit including a front contact of said secondmelay for connecting said one output winding of said saturation relay across the track rails of said rear subsection whereby only coded trackway energy of said advance subsection is cascaded into said rear subsection;

9. In combination with adjoining advance and rear sections of railway track which are electrically separated by insulated rail joints, means for supplying coded current to the rails of said advance section, a saturation relay all of the component parts of which are stationary and comprising a magnetizable core carrying a saturation winding supplied with unidirectional current from the track rails of said advance section in response to said coded current, said core carrying a primary winding constantly supplied with current from an alternating current source, and said core also carrying two secondary windings inductively coupled with said primary winding in such manner that a relatively high electromotive force is induced in one or the other of said secondary windings according as said saturation winding is or is not supplied with unidirectional current, a slow acting two winding relay, a pick-up circuit for a rlrst Winding of said slow acting relay for energizing said slow acting relay in response to the relatively high electromotive force intermittently induced in said one secondary winding of said saturation relay, a slow release relay, circuit means including a front contact of said slow acting relay for energizing said slow release relay in response to the relatively high electromotive force induced in said other winding of said saturation relay, a code detecting relay, circuit means including a front contact of said slow release relay for energizing said code detecting relay in response to the relatively high electromotive force induced in said one secondary winding of said saturation relay, a stick circuit for the second winding of said slow acting relay for energizing said slow acting relay in response to the relatively high electromotive force induced in said one windwith trackway current which ing of said saturation relay having two branch paths one including a front contact of said slow releasing relay and the other including a back contact of said code detecting relay, an energizing source of current for the track rails of said rear section, two coding contacts, circuit means governed by said slow acting relay and by said slow release relay for connecting said energizing source to the track rails of said rear section over one or the other .of said lcoding contacts according as said slow acting and slow release relays are both picked up or are both released, and a circuit including a front contact of said slow acting relay and a back contact of said slow release relay for connecting said energizing source directly to the track rails of said rear section in the event that current feeds over said insulated rail joints from the rear section into the advance section.

10. 'I'he combination with a section of railway track divided into an advance subsection and a rear subsection and provided with means for supplying the track rails of said advance subsection at times is coded and at other times is non-coded, of means for cascading trackway energy from said advance subsection into said rear subsection comprising a saturation relay characterized -by the fact that all its component parts are stationary, said relay comprising a magnetizable core provided with a saturation winding supplied with unidirectional current from the track rails of saidv advance subsection in response to said trackway current, said relay having a primary winding disposed on said core and constantly supplied with current from a. source of alternating current, said relay also having a' secondary winding disposed on said core and inductively coupled with said primary Winding in such manner that an electromotive force of relatively low or high magnitude is induced therein according as said saturation winding is or is not supplied with unidirectional current, and means for connecting said secondary winding across the track rails of said rear subsection.

11. In combination with adjoining advance and rear subsections, means for supplying the rails of said advance subsection with trackway energy which is coded under certain conditions and non-coded under others, a relay of the saturation type comprising a magnetizable core provided with a saturation winding receiving energy from said advance subsection and an input winding constantly connected with a source oi.' alternating current and .an output winding inductively associated with said input winding in such manner that a relatively high voltage is induced in said secondary winding when and only when said saturation Winding is deenergized, and means for connecting said secondary winding with the rails of said rear subsection whereby coded trackway energy from said advance subsection is cascaded into said rear subsection and said rear subsection is supplied with Inon-coded "clearing out energy when said advance subsection is occupied.

12. In combination with a section oi' railway track divided into advance and rear subsections and having means lfor supplying coded trackway current to the rails of said advance subsection. a. source oi' periodically varying current for the rails oi' said rear subsection, and means for inductively coupling said source to the rails of said rear subsection, said means comprising a magnetizable core provided with a primary winding constantly supplied with current from said source, a secondary winding disposed on said core in inductive relation to said primary winding and connected directly across the rails of said rear subsection, and a control winding also disposed on said core and receiving current from the rails of said advance subsection for varying the inductive coupling of said primary and secondary windings in step with the supply of current to said control winding, whereby to cause current induced in said secondary winding and supplied to the rails of said rear subsection to be coded at a rate corresponding to the code rate at which current is supplied to the rails of said advance subsection.

13. In combination with a section of railway track divided into advance and rear subsections and having means for supplying coded trackway energy to the rails of said advance subsection, a source of periodically varying currentv for the rails of said rear subsection, and meansfor inductively coupling said source to the rails of said rear subsection, said means comprising a magnetizable core provided with a primary winding constantly supplied with current from said source, a secondary winding disposed y on said core in inductive relation to said primary wind-` ing and connected across the rails oi.' said rear subsection, and a control winding also disposed on said core and receiving current from the rails of said advance subsection for creating magnetic flux in said core to vary the inductive coupling of said primary and secondary windings in step with the supply oi.' current to said control winding, whereby to cause current induced in said secondary winding and supplied to the rails of said rear subsection to be coded at a rate corresponding to the code rate at which current is supplied to the rails of said advance subsection.

14. In combination with a section of railway track divided into advance and rear subsections and having means for supplying to the rails of said advance subsection periodically varying current coded at one or another of a plurality of rates of coding, a source of periodically varying current for the rails of said rear subsection, and means for inductively coupling said source to the rails of said rear-subsection, said means comprising a, magnetizable core provided with two magnetic circuits arranged in shunt t0 each other, a primary winding disposed on a portion of said core common to both said magnetic circuits, a secondary winding disposed on one oi' said two magnetic circuits o1' said core and connected directly across the rails oi said rear subsection, and a control Winding disposed on the other of said two magnetic circuits and connected through a full-wave rectiiier to receive unidirectional current irom the rails oi' said advance subsection.

CLAUDE M.VH1NES. 

